Alan M Fudge DVM wrote:
> I have Kantronics MT1200G- purchased this spring with intention of
> APRS/digipeating with search and rescue and also packet for emergency
> ham comm. After no response from email and fax from Kantronics
> support- I finally got around to phoning for helpful support for com
> setup
>> Forgive me for calling the comm protocols as archaic, but as a mostly
> Mac user (but purchaser of Vista laptop for SAR mapping, comm, and ham
> stuff), and with Hyperterminal Private Edition installed, I am
> struggling to understand the manual for the correct string to beacon
> APRS via a HT or mobile an the MT1200. I am reading other packets but
> probably don't fully understand the manual.
>> this is the string I have for GTEXT:
> $GA$$CHKSUM$$LAT$$LONG$$UTC$$DATE$$ALT$
> -is that correct? Any errors?
>>> Alan M Fudge DVM
> K6PUG
> El Dorado Sheriff Search and Rescue, California
>>> _______________________________________________
> aprssig mailing list
>aprssig at lists.tapr.org>https://lists.tapr.org/cgi-bin/mailman/listinfo/aprssig
1) A "Vista laptop" is just about the worst possible choice for APRS
applications. Any such laptop most likely does not have any real
physical serial COM ports that are essential to most APRS applications
involving computers, GPS and TNCs. You will be forced to struggle
with the USB-to-serial converter cable "dongles", many of which
imperfectly emulate a real serial port, lack proper driver support for
Vista, or simply don't work with particular applications. Some will
work, but it's far far less hassle to have a real serial COM port in the
first place.
2) Any tracker derived from a TNC like a KPC3 will be a very dumb
tracker tracker inefficiently transmitting raw NMEA strings over the
air, that are over 10 TEN TIMES longer than the compressed Mic-E format
posits generated by a TinyTrak or a Kenwood D7/D700/D710 in it's native
mode. These longer strings are far more likely to NOT be received
successfully since there is a far greater chance that the packet will be
hit by mobile flutter, a pop of noise or get stepped on by other
stations. Further they needlessly occupy more air time on busy APRS
channels than necessary.
3) Note the description of this device as a "Wireless Modem" rather
than a "TNC". This is the tip-off that this device is primarily for
commercial land-mobile NON-HAM applications. The MT-1200 is primarily
intended for commercial AVL (Automatic Vehicle Location) and telemetry
using proprietary protocols. It only makes a token concession to ham
standard operation, primarily for classic "connected" packet rather than
APRS operation.
It only supports basic "dumb" digipeating without the duplicate packet
suppression and WIDEn-N callsign substitution digipeating characteristic
of modern APRS operation. It would be capable of simple WIDE1-1
first-hop home fill-in digipeating. It would not be able to function as
a modern mountain-top WIDEn-N digi in standalone mode
The easiest way to make this thing behave as a fully-functional
digipeater is to let a program like APRSplus or UIview running on a PC
place the TNC into KISS mode, bypassing it's slightly non-standard
firmware.
4) The GPS in this unit is a rather dated unit not using the modern
high-sensitivity SiRF III chipset or equivalent.
I've always though embedding the active RF circuitry of of a GPS
receiver in some other device's box (like a transceiver or TNC) is a
rather perverse concept since it then forces you to deal with the
horrendous coax losses at 1.6GHz to get from the external antenna to the
GPS. Not to mention having to deal with fabricating coax cable
assemblies with those nasty subminiature connectors like SMAs or SMCs
that GPS receiver modules and patch antennas use.
It makes much more sense to combine the patch antenna and GPS receiver
electronics (like a Garmin GPS18 or the low-cost Deluo units) into a
single unit and then run DC power up/serial data down to the other
device, avoiding the coax loss and miniature RF connectors. I.e. a
Garmin GPS-18 all-in-one plugged into a TinyTrak or Kenwood serial port.
--
Stephen H. Smith wa8lmf (at) aol.com
EchoLink Node: 14400 [Think bottom of the 2M band]
Home Page: http://wa8lmf.com --OR-- http://wa8lmf.net
NEW! World Digipeater Map
http://wa8lmf.net/APRSmaps
JavAPRS Filter Port 14580 Guide
http://wa8lmf.net/aprs/JAVaprsFilters.htm
"APRS 101" Explanation of APRS Path Selection & Digipeating
http://wa8lmf.net/DigiPaths
Updated "Rev H" APRS http://wa8lmf.net/aprs
Symbols Set for UI-View,
UIpoint and APRSplus: